As one example of a membrane filtration apparatus that produces a permeated liquid by filtering a raw liquid with use of a membrane element, there is known a membrane filtration apparatus equipped with a membrane element having a membrane roll body formed by winding a membrane member around and a pressure-resistant vessel for housing the membrane element. The pressure-resistant vessel is made, for example, of a tubular shape. Typically, within the pressure-resistant vessel, a plurality of membrane elements are disposed side by side in a straight line along the axial line direction thereof.
The membrane roll body in a membrane filtration apparatus of this type is formed by winding a membrane member around. This may result in a case in which, by a pressure along the axial line direction that is received from the raw liquid or the like flowing through the pressure-resistant vessel, the membrane member may be shifted along the axial line direction, whereby the membrane roll body may be deformed in a telescopic shape. In order to cope with such a problem, there is known a technique such that the shift of the membrane member along the axial line direction is prevented by attaching an edge member (a so-called anti-telescoping member) to face an end surface of the membrane roll body (see, for example, Patent Documents 1 to 3 listed below).
As disclosed in Patent Documents 1 to 3, an exterior finishing material is provided on an outer circumference of the membrane element, and the exterior finishing material is attached to extend across an outer circumference of the membrane roll body and a part of the anti-telescoping member.